Embedded systems are widely used in many fields, from space industry to medicine. In this paper we consider Quality of Service (QoS) in embedded networks. Different QoS are analyzed. The authors consider three structures and implementations of the network layer for providing QoS, compare their implementation characteristics and evaluate hardware costs. They consider QoS mechanisms support in modern space network protocols, possibility of using them in embedded networks. Hardware costs are one of the main constraints for embedded networks. Therefore hardware costs of basic routers with these QoS mechanisms are compared.